﻿// Spun AJAX Framework
// Copyright (C) 2008 Blake Hegerle
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace Formality.FormalSystem
{
    public class Function : TermOperator
    {
        public const string OPERATOR = "juxtaposition";

        public Function(Variable Name, params Variable[] Arguments)
            : this(Name, (IEnumerable<Variable>)Arguments)
        { }

        public Function(Variable Name, IEnumerable<Variable> Arguments)
            : base(OPERATOR, Concat(Name, Arguments))
        {
            this.Name = Name;
            this.Arguments = Arguments;
        }

        public Variable Name { get; private set; }
        public IEnumerable<Variable> Arguments { get; private set; }

        #region Proposition overrides
        protected override TermOperator NewOfThisType(IEnumerable<Proposition> Operands)
        {
            return new Function(Name, Arguments);
        }
        #endregion

        #region Sentence overrides

        public override void Serialize(TextWriter Writer, bool Detailed)
        {
            var Args = Arguments.ToArray();

            Name.Serialize(Writer, Detailed);

            if (Args.Length == 1)
            {
                Args[0].Serialize(Writer, Detailed);
            }
            else
            {
                Writer.Write('(');

                for (var i = 0; i < Args.Length; i++)
                {
                    if (i > 0)
                        Writer.Write(", ");

                    Args[i].Serialize(Writer, Detailed);
                }

                Writer.Write(')');
            }
        }
        #endregion

        private static IEnumerable<Proposition> Concat(Variable Name, IEnumerable<Variable> Arguments)
        {
            return (from Op in Name.Singleton().Concat(Arguments)
                    select Op as Proposition).ToList();
        }
    }
}
